Category Archives: BGP

Another BGP blunder.but not THAT one

Posted on by

Recently, there has been much talk about the Cloudflare BGP blunder and others. The Network Collective even did a video about such things. But did you know there was one involving the entire /12 of IPV6 space? Airtel AS9498 announced the entire IPv6 block 2400::/12 for a week and no-one noticed. Someone typed a /12 instead of a /127.

So why did no one notice? I think part of it is due to the low usage of v6 space.  Sure, all kinds of people claim stats on IPV6 usage.  They talk about X number of traffic is v6, etc. There is a difference between users and connections.  A connection may not actually represent unique users.

Secondly, people are used to IPV6 being buggy.  I know many ISPs who disabled v6 as part of their troubleshooting steps.

I know there will be several folks who jump all over me about IPV6 being the wave of the future and we all should be using it.  Yes, we should, but there is no huge hurry when it comes to business cases.

“Glue addresses” in networking

Posted on by

Imagine this scenario.  You have bought an IP or DIA circuit from someone that is going to provide your network with bandwidth.  Typically this company will make the connection, IP wise, over a /30 or even a /29 of IP space.  I have called this the “glue address” for many years.  This is the IP address that binds (the glue reference) you to the other provider’s network. They can route you IP blocks over that glue address or you can establish BGP across it, but it is the static address which binds the two networks together.

Some network folks call this a peering address.  This isn’t wrong but can infer you are doing BGP peering across the address.  You aren’t always doing BGP across the glue address.

#routinglight #packetsdownrange

Noction: BGP in Large Networks

Posted on by

Are you running a large scale BGP network? Need some tips and help on what to optimize and what your next steps to optimize your setup?

Using iBGP with loopback addresses
Making sure all routers know next hop and loopback addresses
Whether to use route reflectors rather than an iBGP full mesh
Where to originate prefixes
Where and how to filter announcements

Using BGP in large scale networks and how to get the most out of it. Paper by Noction

BGP Monitoring RFC 7854

Posted on by

https://tools.ietf.org/html/rfc7854

   This document defines the BGP Monitoring Protocol (BMP), which can be
   used to monitor BGP sessions.  BMP is intended to provide a
   convenient interface for obtaining route views.  Prior to the
   introduction of BMP, screen scraping was the most commonly used
   approach to obtaining such views.  The design goals are to keep BMP
   simple, useful, easily implemented, and minimally service affecting.
   BMP is not suitable for use as a routing protocol.

How I learned to love BGP communities and so can you

Posted on by
This content is for Patreon subscribers of the j2 blog. Please consider becoming a Patreon subscriber for as little as $1 a month. This helps to provide higher quality content, more podcasts, and other goodies on this blog.
To view this content, you must be a member of Justin Wilson's Patreon at "Access to patro..." or higher tier
Unlock with Patreon

BGP Confederations

Posted on by

In network routing, BGP confederation is a method to use Border Gateway Protocol (BGP) to subdivide a single autonomous system (AS) into multiple internal sub-AS’s, yet still advertise as a single AS to external peers. This is done to reduce the number of entries in the iBGP routing table.  If you are familiar with breaking OSPF domains up into areas, BGP confederations are not that much different, at least from a conceptual view.

And, much like OSPF areas, confederations were born when routers had less CPU and less ram than they do in today’s modern networks. MPLS has superseded the need for confederations in many cases. I have seen organizations, who have different policies and different admins break up their larger networks into confederations.  This allows each group to go their own directions with routing policies and such.

if you want to read the RFC:https://tools.ietf.org/html/rfc5065